The present invention relates to a belt grinding machine which is used to produce belts made of fiber-reinforced rubber and having longitudinally extending ribs and grooves such as V-ribbed belts.
A V-ribbed belt is a type of power transmission belt which has a plurality of V-shaped ribs (separated by grooves) arranged in the longitudinal direction. Thus it looks like a plurality of side-by-side V-belts joined in parallel with each other. Because of its configuration, a V-ribbed belt has the flexibility of a flat belt and the high transmission efficiency of a V-belt.
Such an unevenness (ribs and grooves) of a belt is normally formed by a grinding wheel or a cutter. First a flat or smooth belt is formed, and then the grooves are ground (or cut away).
Up to the present, grinding with a diamond wheel or with a rotary grinding wheel clad with diamond abrasive grains has been considered to be optimal for producing the above-mentioned grooves in belts containing cotton or nylon fibers in the rubber layer. The grinding wheel itself is expensive, but grinding with a diamond wheel is most desirable and efficient when the speed of processing, the cost per one piece of belt, etc. are considered.
The situation was found to be quite different for rubber belts containing fibers of special aramid such as Kevlar and Cornex. When rubber belts containing such a fiber having high strength and a high modulus of elasticity is ground with a diamond wheel, the wheel becomes worn and clogged in a short time because of the fiber. Hence the speed and precision of grinding will deteriorate as well. Moreover, the wear and clogging of the wheel cannot be restored in this case. As a result, the service life of the diamond wheel is reduced to about one hundredth of the life of a wheel used for grinding rubber belts containing nylon fiber. The production cost of the belts, in turn, will rise extremely.